public class DayCode {    public static void main(String[] args) {        String[] words = new String[]{"aaaa","asas","able","ability","actt","actor","access"};        String[] puzzles = new String[]{"aboveyz","abrodyz","abslute","absoryz","actresz","gaswxyz"};        List<Integer> ans = new DayCode().findNumOfValidWords(words, puzzles);        System.out.println("ans is " + ans.toString());    }
    /**     * https://leetcode-cn.com/problems/number-of-valid-words-for-each-puzzle/     * @param words     * @param puzzles     * @return     */    public List<Integer> findNumOfValidWords(String[] words, String[] puzzles) {        Map<Integer, Integer> frequency = new HashMap<Integer, Integer>();
        for (String word : words) {            int mask = 0;            for (int i = 0; i < word.length(); ++i) {                char ch = word.charAt(i);                mask |= (1 << (ch - 'a'));            }            if (Integer.bitCount(mask) <= 7) {                frequency.put(mask, frequency.getOrDefault(mask, 0) + 1);            }        }
        List<Integer> ans = new ArrayList<Integer>();        for (String puzzle : puzzles) {            int total = 0;            int mask = 0;            for (int i = 1; i < 7; ++i) {                mask |= (1 << (puzzle.charAt(i) - 'a'));            }            int subset = mask;            do {                int s = subset | (1 << (puzzle.charAt(0) - 'a'));                if (frequency.containsKey(s)) {                    total += frequency.get(s);                }                subset = (subset - 1) & mask;            } while (subset != mask);
            ans.add(total);        }        return ans;    }}